超细晶铁素体钢的力学性能及成形性能研究

采用形变强化铁素体相变超细晶轧制工艺,获得了750MPa级超细晶铁素体钢板,其超细晶铁素体体积比高达93%,晶粒尺寸仅为1μm,并具有优异的成形性能。对超细晶铁素体钢组织的精细分析发现,因铁素体晶界随晶粒超细化而减薄,使得其晶界对材料的力学性能具有双重影响,一方面,屈服强度随着晶界总长度的增加而提高;另一方面,又因晶界减薄而降低。研究表明,超细晶铁素体钢的组织性能关系虽然与霍尔-佩奇关系相吻合,但存在较大偏差,主要表现为斜率显著下降。文章对斜率下降的原因进行了机理分析。

Study of mechanical properties and forming properties of ultra-fine grain ferrite steels

A kind of ferrite steel plate with ultra-fine grain structure and prominent tensile strength about 750MPa was developed by using deformation enhanced ferrite transformation ultra-fine grain rolling technology.The steel plate's volume percent of ultra fine ferrite is 93% and grain size of ultra-fine grain ferrite is only 1μm,thus enhances the forming properties remarkably.The exact analyzing discovered that ultra-fine grain ferrite steel's boundaries is thinning as grain refining,the effect of grain boundaries on mechanical property present in two aspects:With increasing the grain boundaries total length,the yield strength increase;On the other hand,the yield strength is reducing as grain boundaries thinning.The research results showed that the ultra-fine grain ferrite steel microstructure and properties relation matches Hall-Patch relationship,but there is big deviation.The deviation is the slope of the Hall-Petch decrease obviously.Furthermore,the mechanics analysis about the reason of slope decreasing has been made.